Psychologists and psychotherapists have long relied on the power of narrative storytelling to help their patients make sense of their world. In fact, it's been said that we are our narratives. For evidence that this may be true, pay attention to how people shape their stories about themselves. As it turns out, there is a big difference between the way we narrate events that have really happened to us and those we've invented.

It would seem reasonable to assume that memories, like stories, have a beginning, a middle, and an end. But reason doesn't have much of a role in guiding memory. Avinoam Sapir is a former Israeli police officer, a lie- detection expert, and the developer of Scientific Content Analysis (SCAN), a technique designed to interpret deception in written statements. Sapir notes that true stories drawn from real memories aren't typically narrated in chronological order; that's not the way the brain organizes them. The more dramatic the story, the less chronologic its structure. Why? Because our emotions guide our memories. The more powerfully we experience an event, the more likely we are to make it the first thing we talk about, filling in the less emotionally fraught details later.

That's not to say that any story that doesn't start with high drama is a fabrication. But truthful stories—though they may not be told in chronological order—will still contain three distinct stages: a prologue, a main event section, and an epilogue.

The Prologue

Whether it contains details from the beginning or the end of the story, the prologue sets the scene for the main event. This part of the story is usually light on detail when someone is telling the truth. It should only take up about one—third, or less, of the total time it takes to tell the whole story. In a lie, however, the prologue might be quite detailed. This is often where the liar's story contains a lot of truthful elements, such as time and place. The liar feels comfortable in this relative safety zone—after all, he's not lying yet. He will spend as much time as possible here.

The Main Section

The main event section that follows in a truthful story is normally the longest part, since it's the whole point of telling the story, and is where most of the action lies. In a false narrative, the main event section is often glossed over. An unusually short main event section should give a liespotter pause. It's the part of the story that answers the question, "What happened?" Under truthful circumstances, therefore, it should be the focus of someone's account.

The Epilogue

Last, an honest storyteller will usually provide an epilogue. While it's unlikely to be the most dramatic part of his account, the epilogue can be very emotional—possibly even more emotion-laden than the main story. Often, when we experience frightening or surprising events, we're so caught up in what's happening to us that we don't have time to pro cess how we feel about them. It's only later, once a perceived threat has passed, that we'll calm down enough to be able to acknowledge the emotions that have been triggered.

Therefore, those emotions are likely to crop up as we describe the aftereffects of the main event. Ninety percent of the time, a liar's story will not include an epilogue; he'll simply conclude with the main event. An epilogue would require him to fabricate the way the event affected him. But of course it didn't affect him at all, because it never really happened—or at least it didn't happen the way he says it did. Liars will do their best to avoid lying unnecessarily, so once they think they have said what needs to be said, they'll stop talking. True stories are often jumbled and filled with irrelevant as well as sensory details. Deceptive stories are often logical and streamlined, yet lacking in vivid sensory descriptions.

Pamela Meyer is founder and CEO of Calibrate, a leading deception detection training company, and of social networking company Simpatico Networks. She holds an MBA from Harvard, an MA in Public Policy from Claremont Graduate School, and is a Certified Fraud Examiner. She has extensive training in the use of visual clues and psychology to detect deception.